From 14d066c3531a87f727968cacd85bd95c75f59843 Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Tue, 27 Feb 2018 18:58:14 +0100 Subject: [PATCH] s390/qeth: fix double-free on IP add/remove race Registering an IPv4 address with the HW takes quite a while, so we temporarily drop the ip_htable lock. Any concurrent add/remove of the same IP adjusts the IP's use count, and (on remove) is then blocked by addr->in_progress. After the register call has completed, we check the use count for concurrently attempted add/remove calls - and possibly straight-away deregister the IP again. This happens via l3_delete_ip(), which 1) looks up the queried IP in the htable (getting a reference to the *same* queried object), 2) deregisters the IP from the HW, and 3) frees the IP object. The caller in l3_add_ip() then does a second free on the same object. For this case, skip all the extra checks and lookups in l3_delete_ip() and just deregister & free the IP object ourselves. Fixes: 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback") Signed-off-by: Julian Wiedmann Signed-off-by: David S. Miller --- drivers/s390/net/qeth_l3_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c index 34481b51029e3..77cdb4fc7721e 100644 --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -237,7 +237,8 @@ int qeth_l3_add_ip(struct qeth_card *card, struct qeth_ipaddr *tmp_addr) (rc == IPA_RC_LAN_OFFLINE)) { addr->disp_flag = QETH_DISP_ADDR_DO_NOTHING; if (addr->ref_counter < 1) { - qeth_l3_delete_ip(card, addr); + qeth_l3_deregister_addr_entry(card, addr); + hash_del(&addr->hnode); kfree(addr); } } else {